Turbine blades are the primary elements of wind turbines for converting wind energy into electrical energy. The blades have a cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the blade. The lift force generates torque on the main rotor shaft, which is geared to a generator for producing electricity.
Modern wind turbines can be quite large, with many designs having a rotor hub height exceeding 100 meters, and rotor diameters in excess of 80 meters. The blades have a root section mounted to rotor hub, with the aerodynamic shape of the blades defined radially outboard of the root section. This configuration results in a central “dead” wind zone that is coaxial to the rotor hub wherein virtually no energy is extracted from the wind by the blades. This dead zone can have up to, for example, a 5 meter radius.
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention and importance in this regard. However, the cost/benefit economics of wind energy is a constant consideration. The cost of producing the energy cannot outweigh the benefits. In this regard, the industry would benefit from improvements or advancements in wind turbine design and operation that would utilize the energy from the central dead wind zone to increase the output of the wind turbine.